The traditional small digital igniters for gasoline engines adopt MCU as the core control unit, to provide appropriate ignition signals for the normal operation of a gasoline engine. It can identify the shutdown signals through a flameout port connected to an external flameout switch, to stop a running engine. However, it needs external interfaces to achieve operations of controlling MCU internal data of the igniter, such as reading, modifying, etc., and the circuit is very complicated.